Our current rotavirus vaccination strategy involves the use of an animal rotavirus strain of simian origin in combination with three human rotavirus-rhesus rotavirus reassortant strains to form a quadrivalent vaccine in an attempt to achieve protection against each of the four medically important VP7 rotavirus serotypes. If this approach which relies on the induction of antibody to rotavirus outer capsid protein VP7 fails to achieve the desired level of protective efficacy, we are considering an alternative strategy: the use of one or more cold-adapted human rotavirus mutants. These mutants would possess the human rotavirus VP4 (whereas the quadrivalent vaccine possesses the rhesus rotavirus VP4), an important outer capsid protein that may be important in the induction of heterotypic immunity. It is important to develop an animal model that develops diarrhea following oral administration of a virulent human rotavirus strain in order to determine if the cold-adapted human rotavirus mutant is attenuated. We administered a virulent VP7 serotype 1 human rotavirus strain to two susceptible chimpanzees by the alimentary route. One chimpanzee developed loose stools four to six days after inoculation, shed rotavirus on day 2 to day 7, and developed a seroresponse to the serotype 1 virus. The other chimpanzee developed loose stools beginning on the third or fourth day that subsided before the fifth day after inoculation. The latter animal did not shed rotavirus and failed to develop a seroresponse to serotype 1 rotavirus by PRN assay.